Hybrid electric vehicles are used in the passenger car market and are continuing to expand in the marketplace globally with much success. However, use of hybrid electric vehicles in commercial fleets, such as commercial trucks, vans, utility vehicles, is not well developed which has created opportunities for those interested in developing improved systems for such commercial applications. Also, in the commercial fleet vehicle market, plug-in hybrid electric vehicles are not well known as engineering barriers continue to exist which have prevented any scaled application of a PHEV into that market.
One of the problems with the use of PHEVs in the commercial truck market is that fleet vehicles in different business settings require certain performance requirements. For example, in the standard internal combustion engine (ICE) commercial truck business, ICEs are utilized as the primary engine plant for propelling a commercial vehicle for both long distance and short distance applications. In particular, a short distance application could be a UPS® truck, a FedEx® truck, a local delivery truck, a utility vehicle, a U.S. postal office vehicle, or the like. Many commercial vehicles will travel in a given day a predetermined route through the city or countryside. The driver routinely knows her exact stops and the number of miles to be traveled each day. Thus, in many of these commercial applications the company that operates these fleet vehicles understands a preset driving pattern which is predictable.
The use of an internal combustion engine in fleet operations is very inefficient and costly, particularly in view of the increase in diesel fuel and gasoline prices. It would be desirable to provide a PHEV system for commercial fleet vehicle applications that utilizes an integrated propulsion device including an internal combustion engine in combination with electric machines to satisfy peak vehicle load needs as well as to reduce energy consumption. Over a fixed battery capacity purely electric vehicle, this combination also extends the usable range for use variations such as peak seasonalities or for emergency response.
It would also be desirable to provide a vocational use power take-off system that is powered by an integrated propulsion device. In this instance the integrated propulsion device can be an internal combustion engine that is combined with one or more electric movers. The electrically driven power take-off system that is powered by the integrated propulsion device can be used for providing power to auxiliary equipment where it is desirable to have a vehicle that is capable of not only traveling down the road, but also to be utilized as a work vehicle, such as a utility truck that requires an auxiliary power supply to provide hydraulic pressure for various vocational equipment or electrical power generation at a job site. Thus, the integrated propulsion device operates not only to propel the vehicle, but also to provide an auxiliary electrical or mechanical power source, on an as needed basis.